The present invention relates to the field of fuel injection for an internal combustion engine, and more particularly to an improved fuel injector with an improved electronic control circuit for use in delivering fuel to a combustion chamber of an internal combustion engine.
Typically, internal combustion engines receive a mixture of vaporized fuel and air from a carburetor which controls the proper ratio of the air-fuel mixture. However, properly delivering this air-fuel vapor mixture to individual cylinder combustion chambers of the engine can present problems. Also, such systems have difficulty in maintaining the proper air-fuel vapor mixture, especially at extremely high or low temperatures. To avoid some of these problems, some prior fuel control systems have utilized direct liquid fuel injection into the engine cylinder combustion chamber. While these systems generally provide improved engine performance, they may not provide efficient fuel combustion. In addition, typically controlling the amount of liquid fuel injection and the time of occurrence of the fuel injection in such systems has been extremely complex and dependent upon a large number of mechanical linkages. These linkages, in time, tend to wear and thereby degrade engine performance.
The electronic control circuits for prior fuel injection systems, such as those discussed above, are generally microprocessor controlled. Typically a microprocessor produces one signal for controlling the amount of fuel to be injected and a separate additional signal for controlling when the fuel is to be injected for direct fuel injection. Some systems produce a single control signal for controlling both the magnitude of fuel injection and its time occurrence. However, these systems typically rely on many mechanical linkages to properly implement fuel injection in response to such a single control signal, and, therefore, these systems are not very accurate and are subject to mechanical wear.
A new fuel injection system has been proposed wherein liquid fuel is injected into the engine cylinder through the use of compressed air forcing an air and fuel mixture through a spray nozzle. While this has resulted in partial atomization of the liquid fuel to obtain improved combustion, a complex mechanical configuration is utilized to control the amount of fuel to be injected. In addition, it appears that the control circuit for such a system would apparently require a microprocessor to provide a large number of separate fuel amount and fuel injection occurrence control signals for controlling each injector utilized in such a system. Since the microprocessor must produce a large number of fuel injection control output signals, this therefore limits other engine control functions which could be accomplished by the microprocessor.